Whisk the first four ingredients together until thoroughly mixed. Whisk the cream until medium (not quite firm) peaks form. Take 1/4 of the cream and whisk it into the lemon mixture to lighten/loosen it. Fold in the remaining cream and refrigerate for at least an hour.
Meanwhile, crush pistachios and cookies with a rolling pin, until they are reasonably fine. These will be used for layering.
When lemon fluff has chilled, layer it in dessert dishes or wine glasses with the nut/cookie mixture. Return to the fridge for at least 3 hours before serving. Sprinkle top with berries or fruit if desired (pomegranate used here).
Yield: 4-6 servings